SEI growth on Lithium metal anodes in solid-state batteries quantified with coulometric titration time analysis

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium-metal batteries with solid electrolytes offer high energy density but face challenges from parasitic side reactions at the lithium metal anode.
• Understanding and quantifying these side reactions is crucial for improving the safety and lifespan of advanced battery systems.

Purpose of the Study:

• To develop and demonstrate a novel electrochemical method for characterizing parasitic side reactions on active metal electrode surfaces in solid-state batteries.
• To assess the method's applicability in anode-free lithium metal cells and its potential for analyzing electrolyte and current collector interactions.

Main Methods:

• Development of a new electrochemical technique to measure charge consumed by parasitic reactions.
• Validation of the method using an anode-free stainless steel ∣ Li6PS5Cl ∣ Li cell.
• Complementary post-mortem analysis of the solid electrolyte interphase (SEI) microstructure.

Main Results:

• The presented electrochemical method successfully characterizes side reactions on lithium metal anodes.
• The method is viable in practical battery configurations like anode-free cells.
• Analysis revealed the heterogeneous/layered microstructure of the SEI.

Conclusions:

• The new electrochemical method is a valuable tool for investigating electrolyte side reactions in solid-state lithium metal batteries.
• This technique can also be applied to study lithium dendrite formation and analyze different electrolyte/current collector combinations.
• The findings contribute to the advancement of safer and more efficient solid-state battery technologies.